[PATCH 0/2] Recover DP output after a cable replug

[Yashas D <y-d@ti.com>]

Applications that don't run a hotplug event loop (e.g. kmstest, or any
client that just holds a CRTC open without listening for uevents) never
see a display come back after a DP cable is unplugged and replugged.
The bridge's own link state goes down on removal, but nothing tells it
to retrain when the cable comes back unless something above it issues
a fresh atomic commit -- which these applications never do.

Patch 1 (improve HPD interrupt handling) fixes the interrupt handler
to clear all three IRQ status registers instead of just one, so the
IRQ pin is fully de-asserted and doesn't stay stuck; adds detection of
the bridge's separate replug event (a short unplug/replug that doesn't
always cross the debounce threshold used for insertion/removal); and
switches from polling every connector on the device to notifying only
the DP connector that actually had the event.

Patch 2 (retrain DP link directly on cable replug) adds a work handler
that retrains the DP link and re-enables the video stream directly
from the HPD interrupt path when the pipeline is still active, without
waiting for a new atomic commit. This is the piece that actually fixes
the recovery problem described above -- applications with no hotplug
handling get their display back without doing anything.

Yashas D (2):
  drm/bridge: ti-sn65dsi86: improve HPD interrupt handling
  drm/bridge: ti-sn65dsi86: retrain DP link directly on cable replug

 drivers/gpu/drm/bridge/ti-sn65dsi86.c | 227 ++++++++++++++++++++++----
 1 file changed, 193 insertions(+), 34 deletions(-)

-- 
2.34.1